Rand Paul's neighbor pleaded not guilty to assault amid widening questions about what led to the attack

Republican Sen. Rand Paul's next-door neighborhood pleaded not guilty on Thursday to charges that he assaulted the Kentucky lawmaker.

Many details surrounding the incident, including the neighbor's motives, remain undisclosed.

Sen. Rand Paul's next-door neighbor pleaded not guilty on Thursday to charges that he assaulted Paul while the Kentucky Republican was mowing his lawn in Bowling Green last Friday.

Rene Boucher, a 59-year-old retired anesthesiologist who has been neighbors with Paul, an ophthalmologist, for 17 years, was charged with misdemeanor fourth-degree assault, but his motives for allegedly committing the crime remain elusive.

Some of Paul's neighbors told the outlets that reports of a landscaping dispute were "erroneous and unfounded."

"The Pauls are and always have been great neighbors and friends. They take pride in their property and maintain it accordingly," Travis Creed told Breitbart. "Rand has enjoyed working on and maintaining his lawn for as long as I have known him. He was attacked on his property for no apparent reason and suffered serious injury. That is the only fact known at this time."

Paul's injuries are also more severe than was reported over the weekend and earlier this week. On Wednesday, the senator tweeted that he had a pleural effusion, which is a fluid build-up around the lungs, and six broken ribs instead of five, in addition to bruised lungs. His recovery will likely take months.

Jeff Jones, a registered nurse who worked with Boucher, told The Washington Post that Boucher's politics were "liberal" and that Boucher "was active on social media and said some negative things about the Republican agenda" leading some to suggest the attack was politically motivated.

But Boucher's lawyer said in a statement on Monday that the incident had "absolutely nothing to do with either's politics or political agendas" and described the dispute between the two men as "trivial."